1. Technical Field of the Invention
The present invention relates to a multi-plate clutch system that transmits or discontinues the transmission of the drive power from an input member. More particularly, the present invention relates to a multi-plate clutch system equipped with a cam mechanism that suppresses reverse drive power coming from the output member from acting on the input-member side.
2. Background Art
A number of clutch systems including multiple plates are known. One example of a known multi-plate clutch system, described in Japanese Laid-Open Patent Application 2005-325993, has a protruding cam and a recessed cam formed respectively in a pressure plate and in an outer clutch member. Each of the cams has a contact face inclined towards the rotational direction. In the multi-plate clutch system, the clutch capacity is increased or decreased by the torque fluctuations caused by drive power from the crankshaft and reverse drive power from the wheel side.
In the multi-plate clutch system disclosed in Japanese Laid-Open Patent Application 2005-325993, the cam faces of the protruding cam and the recessed cam, each of which is formed in a plane shape, are brought into face contact with each other. By use of the inclined angle, and variation in rotation between an output-shaft side and an input-shaft side, the clutch plates are pressure-contacted with each other or moved away from each other to make the clutch capacity variable. However, in a case where a plurality of cam faces are formed in the circumferential direction, variation in processing accuracy causes changes of the point and in the area of the contact between cams. For the purpose of maintaining the variable characteristics constant, a machining center with a high processing accuracy and a production management system with a rigidly set post-processing management standard are required. As a result, it is difficult to reduce the manufacturing cost and to improve the productivity. In addition, the configuration depends mainly on face contacts, so that the friction contributes heavily to the operation of the cams. Accordingly, when ideal operational characteristics are set, in addition to the setting of the cam angles, friction under various conditions has to be taken into consideration.
The present invention is made in light of the difficulties with the prior art. One object of the present invention is to provide a multi-plate clutch system that maintains constant variable characteristics of the clutch capacity, even when there is a variation in processing accuracy at the time of the production. In addition, the multi-plate clutch system hereof can be produced with a lower production cost and with higher productivity.